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In this work, we present the study of undoped and Fe-doped SnO2 polycrystalline films grown by direct-current sputtering on glass substrates. X-ray diffraction (XRD) analysis revealed that the as-deposited films exhibit an amorphous phase, whereas, after 2 h of thermal annealing at 500 °C, the films showed a rutile-type structure with no evidence of secondary phases. Rietveld refinement analyses of the XRD patterns revealed that the undoped films do not reveal a preferred orientation as is displayed in the bulk system, whilst the Fe-doped films showed a (1 0 1) preferred orientation which is enhanced with the deposition time (film thickness). A detailed analysis revealed a clear dependence of the unit cell volume on the crystallite size. The latter effect was mainly associated with strain effects occurring during the film deposition. Additionally, the growth of columnar-shaped structures was determined by cross-section scanning electron microscopy images. Interesting features of the fundamental absorption were determined via UV–vis spectroscopy. The obtained results revealed a monotonous decrease of the band gap with film thickness, which becomes larger for the Fe-doped SnO2 films and is associated with a change in the residual strain, in good agreement with the XRD analysis and Raman spectroscopy measurements.

Delafossite CuAlO2 is a p-type transparent semiconductor oxide with space group R-3m (N°166) is a material with extended applications in different fields. Structural parameters, band structure, and density of CuAlO2 have been investigated in the light of the Density Functional Theory (DFT) using PBE pseudopotentials (norm-conserving pseudopotentials). Our calculations are performed with the ABINIT package using cut-off energy of 100 Hartree, showing convergence to cut-off energy up to 30 Hartree. The lattice parameters of CuAlO2 obtained after the relaxation process are a = b = 2.904 Å and c = 17.202 Å; and consequently, volume of V=174.014 Å3 , also the derivate of the bulk modules Bo´=4.1, and bulk modulus Bo=174 Gpa were found. We find that discrepancies between our calculated lattice parameters a, c, and c/a are overestimated about 0.798%, 0.591%, and 0.219% compared to the reference’s theoretical calculations of Qi-Jun Liu et,al respectively. The calculated energy band structure of CuAlO2 and the high-symmetry points of Brillouin Zone show that the delafossite structure has an indirect band gag (~ 1.21 eV) because the top valence and the bottom conduction are found at F point and Г point, respectively. This work aims to study structural parameters, band structure, and density of states of delafossite CuAlO2 and give one application as solar cell.